Improvement of blasting efficiency with pre-softening of rock mass

Abstract

The substantiation is given support preliminary softening of rock mass to enhance blasting efficiency. The proposed technology was subjected to pilot testing in Ayak-Kodzhan mine, Republic of Kazakhstan. A total of 5 explosions were carried out using the technology with preliminary softening and 5 explosions were executed using the standard technology, with variation in drilling and blasting parameters to determine the optimized drilling and blasting pattern design toward enhanced blasting efficiency. In processing the data of pilot explosions, the dependences of the oversize yield and powder factor on the least burden were obtained using the standard and proposed technologies. Based on the experimental blasting, it can be concluded that the best fragmentation quality is achieved during the first experimental explosion with a drilling pattern 4×4 m and with the use of additional boreholes for preliminary softening of rock mass. The oversize yield is 0.6%. However, during this explosion, the highest powder factor is recorded—1.36 kg/m3. The best economic parameters are obtained in the second experimental explosion with the borehole pattern 4.5×4.5 m. In this case, the oversize yield is 0.8% and the powder factor is 1.05 kg/m3. Moreover, the excavation velocity is increased by 10% as a result. The authors obtain the relationship of the oversize yield and the powder factor with the least burden in the technology with preliminary softening of rock mass. The practical significance of the study lies in the justification of the blasting technology with preliminary rock mass softening and in the optimization of drilling and blasting design to achieve the required fragmentation quality.The authors express their gratitude to NPP Interrin management represented by CEO P. G. Tambiev for the help and contributory influence during pilot testing.